A major effort will continue to be the use of charged particles from the RARAF accelerator at Brookhaven National Laboratory; protons, deuterons and 3He ions in the track segment method with defined LET values from 10 to 155 keV/microns. The next step will be to use cells synchronized by mitotic selection in order to confirm and extend the data obtained with hydroxyurea-synchronized cells to other phases of the cell cycle. Further measurements of microdosimetric quantities are planned for high energy Carbon and Neon ions accelerated at the BEVALAC. Experiments with the in vitro transformation system will focus attention on the use of tumor promoters and an evaluation of protease inhibitors and their effect on the yield of transformations. A continued effort will be made to develop and use human cell lines that can be transformed by radiation.